Numerous ducts and tubes for transporting abrasive materials from one place to another are known in the prior art. However, each of the prior art tubes and ducts suffers from one or more serious disadvantages ma-king them less than entirely suitable for their intended purpose.
For example, transport ducts made entirely of ceramic, metal or polymer materials have been utilized for many years. Although ducts made from alpha alumina are wear resistant and not easily corroded, they are susceptible to internal buildup of ceramic powder. In addition, they are not easily bent into desired shapes. Metal ducts are expensive and susceptible to corrosion and wear by ceramic particles. Polymer ducts are readily worn away by ceramic powders unless the ducts are reinforced with ceramic elements.
Several prior art patents disclose composite transport tubes different from those claimed herein. For example, van Waveren U.S. Pat. No. 4,564,319 shows a flexible tube for transporting a mixture of liquid and solid materials containing sharp edges or projections. The tube is principally rubber and has ceramic or steel rod-shaped elements which extend from the inner surface to the outer surface of the rubber tube perpendicular to its axis. The flexible tube is used as a pipeline with a length of some hundreds of meters for offshore dredging operations.
Some other wear-resistant composite transport pipes are disclosed in West German Patents 3,530,987 and 3,901,618; Japanese Patent 1-150,622 dated Jun. 13, 1989; and Australian Patent 434,829.
It is a principal objective of the present invention to provide a transport duct suitable for carrying abrasive materials and providing improved wear resistance.
A related objective of the present invention is to provide a transport duct comprising an axially extending array of alternating ceramic and polymer segments.
Additional objectives and advantages of the present invention will become apparent to persons skilled in the art from the following detailed description.